Download or read book Studies on the Ontogeny of the Mouse Immune System written by M. L. Tyan and published by . This book was released on 1968 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: The presence of potential immunologically competent cells in the various tissues of embryonic, newborn and adult mice was demonstrated by means of a modified 'graft-vs-host' method and by the injection of chromosomally marked cells into irradiated recipients. The results indicate that lymphoid stem cells which have the potential to participate in cell-bound immune reactions appear in the placenta and liver by the 9th or 10th day of gestation. Throughout pregnancy they are found in the liver. During the 11th to 14th days of gestation these stem cells are present in the upper trunk or in the thymus. On about the 15th day they appear in the lung and toward the end of the pregnancy in the fetal bone marrow and spleen. There was little or no evidence of the presence of lymphoid precursors capable of maturation to cells which mediate cell-bound immune responses in the gut prior to birth. Following parturition lymphoid stem cells were present in the liver, Peyer's patches, lung, bone marrow, lymph nodes, spleen, blood and thymus. However, by six weeks after birth the bone marrow appeared to be the major or sole source of these cells. Certain of the data suggest that immunoglobulin producing cells (as opposed to those which mediate cell-bound immunity) may arise in the yolk sac on the 9th or 10th day of gestation. Further, these immunoglobulin producing cells may reside in the gut as a relatively pure cell population after the 16th day of gestation. (Author).